Rough 5spd Shifts -- out of ideas!

Hi, I have read this forum for years, but this is my first time posting. Thanks to everyone for giving input over the years on our vehicle(s).

I have a 2003 V6 4x4 5-speed manual, and the shifts have been very rough lately, and I cannot figure out why. The truck is at about 175,000 miles; I have owned it since 100,000 (bought about a decade ago) and keep up regular maintenance.

Symptoms of the rough shifting:

• I don't notice it in any gear in particular, and it does not seem to matter whether the transmission is hot or cold.
• Periodically, but not regularly, shifts will make a "clunk" sound--they are usually very rough shifts when this happens.
• Every now and then a shift acts like I let out the clutch way too early/late. I can't replicate this regularly, though.
• Perhaps 1-in-10 drives everything seems to be shifting smoothly/quietly.

I have:

• Replaced transmission and transfer case fluids with MT90 (I noticed no difference)
• Replaced the center bearing (this seemed to help)
• Had the clutch, pilot, and throw-out bearings replaced by a trusted mechanic (I thought this fixed it, but started noticing issues again after a couple hundred miles)
• Replaced the shift seat with the Marlin Crawler set (I noticed no difference)

The only thing I've seen that I've not tried is replacing the clutch fluid. I do not know if the mechanic did this when he replaced my clutch.

I am hoping you all can give me some new ideas/fixes to try; with all my searching and reading, I'm out of ideas.

Thank you in advance!

 

Have you checked if the transmission or engine mounts need replacing? Have you replaced the shifter bushing?

 

Hi, yes, I used a pry bar on the transmission mounts and they had very little play in them. Visually, the rubber blocks look to be in very good condition.

Assuming you're talking about the plastic ring at the bottom of the shifter, I replaced the shifter bushing and seat with the Marlin Crawler set that's regularly recommended on here.

Thanks again.

 

Could you describe the 'rough shift' in a little more detail? How is it rough, what happens, how often (ie, once in how many-ish shifts), any difference between up-shifting & down-shifting?

 

When you say "rough shift" is it shaking the truck after it goes in gear? I had a similar situation and changed out the center support bearing on the driveline and the trans mount, but the biggest improvement was the tires. My tires were old and dried out and when I put the new ones on, the shakiness/vibration went away.
Just my .02

 

Have you looked for a broken Firewall or broken Clutch bracket??

Just being lazy with the clutch pedal?? I have found a change in foot ware I find myself doing this. Since most my driving is my work boots my sneakers need a longer pedal stroke .